There are a lot of different ways to sharpen images in Adobe Photoshop. In this article I’m going to share one of my favorite methods which uses the High Pass filter. Photoshop offers a number of filters and tools dedicated directly to sharpening images, so it might seem strange to use the High Pass filter, but this method has definite advantages for some images.
High Pass sharpening does an excellent job of bringing out detail and it’s my favorite tool for architectural shots. High pass sharpening also allows you a lot of visual control of your sharpening. How the sharpening is applied and even where its applied can all be controlled and adjusted non-destructively after the fact, with real time visual feedback. High Pass sharpening can be very strong and very powerful. This is important to keep in mind because it is very easy to over sharpen your image, especially in areas with very fine details or textures.
Step 1: Duplicate your Image Layer
To get started with high pass filter you need to open your image in Adobe Photoshop. If your image contains multiple layers you will need to flatten the image. Next duplicate your image layer.
Step 2: Select the High Pass Filter
The High Pass filter is an obscure filter buried under the “Other” sub-menu of the Filter menu. It’s generally overlooked and if you’ve ever experimented with it you may have ended up with some strange results. But now we are going to put it to good use in this sharpening process. Make sure the top layer is highlighted and select the High Pass Filter.
Step 3: Select the Radius Value
The next step is to select the radius value for the High Pass filter. The radius value is somewhat subjective but something you will get a feel for with practice. The correct radius value will allow you to see the detail and edges of the subjects in your image. But the line will appear thin and embossed rather than thicker like an actual outline.
A radius of 4 is a good general starting point. You will find images with very fine textures and large flat areas, or images of people may need a smaller radius. Images with larger textures and architectural images may be able to stand a slightly higher radius.
There is a range of acceptable radius values. Sharpening itself is somewhat subjective and you will still have some additional control over the sharpening after the filter is applied. If in doubt, choose a smaller radius over a larger. As we proceed through the steps if you find that your image contains white fringes or “halos” then it is a sure sign your radius is too large.
Once you have the radius selected click “Ok” to apply the filter.
Step 4: Change the Layer Blending Mode to “Overlay”
Make sure the top layer (the one with the High Pass Filter applied) is highlighted, then change the blending mode to “Overlay”.
If you are happy with the result then you can stop here and enjoy your sharpened image. You can toggle the layer on and off (using the eye to the left of the layers thumbnail image) to better see and evaluate the effect of the sharpening. Look for too much contrast or for white fringing that signal an over-sharpened image.
Step 6: Adjusting the Sharpening
As I mentioned in the beginning of this article, one of the things I love about the High Pass sharpening method is how adjustable and flexible it is. Here are some ways you can try to adjust and control your image sharpening:
- If your image appears over-sharpened and you want to reduce the sharpening effect you can simply reduce the opacity of the High Pass layer. This will work unless the problem is that white fringing as discussed earlier. That is caused by using a radius that is too large, and the only way to fix this is to go back and start again with the High Pass Filter set to a lower radius value.
- If you are having trouble selecting a radius value, you can reverse steps 2 and 4. Changing the blending mode to “Overlay” before applying the High Pass filter will allow you to preview the sharpening effect while you adjust the slider to select your radius value.
- You can try setting your blending mode to Soft Light instead of Overlay. Soft Light creates a more subtle and lower contrast sharpening.
- You can add a layer mask to eliminate or reduce the sharpening in certain areas of your image.
Before and After Sample Images
High Pass sharpening is a fairly simple process once you are familiar with the steps. It works especially well on architectural images and cityscapes, although I have used the process successfully on many different types of images. If you have tried this method of sharpening I would love to hear your thoughts!
Changing the newly copied layer to a smart object prior to applying the High Pass filter will also allow you to meet dynamically make changes to the radius size if you want to adjust the results!
Gill Thompson
Images by Chaos
Great suggestion! I will have to try that.
It is worthwhile to point something out.
After you create the Background Copy layer, set it to Overlay mode.
Do this BEFORE you create the High Pass filter.
This allows you to see the effect of the HP filter by varying the Radius size.
Good suggestion- I mentioned this later in the article (in the section on adjusting the sharpening) and It works well. I have found that once I got used to how the high pass filter should look when the radius is correct, it’s actually faster to set the radius without the layer set to “Overlay” (the gray embossed look makes it very easy to see how thick the outline is, which I prefer) but I may be in the minority on that one!
I agree the high pass filter is a great sharpening technique. I would say one thing, with regards working non-destructively I would not recommend flattening the image in the first step but rather use the “apply image” tool from the menu to create a duplicate of all the layers onto one new layer. That way if you later want to make changes to your image you can do, whereas with the flattened image that would be very difficult to do.
But a good article on making everyone aware of this hidden sharpening method.
This technique was quite common in the early days of digital imaging. Especially when You had for an example a face where the sharpness was placed I bit behind the eyes (very common before autofocus or early days autofocus). You then just selected/marked the eyes and the mouth and applied some sharpness with the High Pass filter on the selected parts in the picture. The filter then increase the contrast between found pixels, and “voila”, it looks sharper and is possible with the normal sharpening tools to make a picture printable with excellent results. Print houses also used this method frequently when scanning slides. Even today You can use the same method to increase sharpness in a picture where where the sharpness is in the wrong place…
FYI – You can also use this technique for blurring if you Invert the duplicate layer.
I also use this way of sharpening, but what it does in a way ; it turns a continu tone photo into a staccato drawing.
Sharpness is important, but like all sharpning methods this one too has a downside.
If i use it, I never use a radius more than 1 pixel and start at 0.3 to enhance mine.
Thanks, these are the kind of articles I like to see, those that help me improve my photography, my post-processing, or learn about new or useful equipment. I routinely use the lens reviews and comparisons when considering a new lens. I don’t particularly care for the how to shoot this or that location.
Hi Meg
Got an amazing result! Thank You, much appreciated
I reduced sharpening in a LR image to 0
Then used your sharpening method
Regards,
Gary
Cool! and it works fine in Gimp too.
You’ll find the high pass filter in Filters, G’MIC, Detail.
Thanks!
Great video. I practiced by taking a picture of my grandson playing baseball. I followed all of your steps and noticed two things: 1) The sharpening effect of his face and name on his jersey was FANTASTIC. However, it seemed to introduce noise to his baseball cap and rest of jersey. Easy fix as someone was alluding above: I simply added a mask, hit Control I to invert, insured the foreground on color was set to default, i.e. white foreground with black background, switched to brush and then simply painted in the sharpening to his face and lettering on jersey. Again, thanks for great tip.
I use another method. Convert the desired image temporarily to Lab Color Mode. Then select only the Lightness Channel e.g. diasable the other channels Lab, a + b. Apply an unsharp mask to your needs. After that select all channels again and convert the image back to RGB Color.
Works fine for me.
Great article Meg. I use Affinity photo, and exclusively use high pass sharpening. For affinity, the radius works well between 0.5 and 1, and I can then experiment with 4 different blend modes – Overlay, Soft light, Hard light and Linear light. Linear light gives most sharpening and soft light a more subtle one. I am unable to distinguish between overlay and hard light.